Surfacing means



March 18, 1941. M. H. BIRGER ETAL 2,235,446

SURFAGING MEANS Filed July 10, 1959 4 Sheets-Sheet l March 18, 1941. MBIRGER ETAL 2,235,446

SURFACING MEANS Filed July 10, 1959 4 Sheets-Sheet 2 March 18, M HB|RGER ETAL SURFACING MEANS Filed July 10,1959 4 Sheet s-Sheet s March18, 1941.

M. H. BIRGER ETAL SURFACING MEANS- Filed July 10, 1939 \grl 4Shets-Sheet 4 Patented Mar. 18, 1941 UNITED STATES SURFACING MEANSApplication July 10, 1939, Serial No. 283,560

10 Claims.

This invention relates to surfacing means, and with regard to certainmore specific features, to surfacing means for concrete or the like.

Among the several objects of the invention may be noted the provision ofa method of surfacing, and apparatus therefor, in whichcomminutedmaterial obtained by a grinding IOI' abrasive action on asurface is conserved in situ, and which is promptly trowelled intoposition within voids which are broken open by the grinding or abrasiveaction or which may have been left by water or air bubbles in placing ofthe concrete; the provision of surfacing means of the class described,whereby at a single operation a smoothing and dressing is accomplished;the provision of means of the class described which may be made ineither manually-operated or power-operated forms; the provision of meansof the class described which is easier to operate than the meansheretofore used for analogous purposes, yet which provides a smootherand better finish, all at much reduced cost; and the provision of meansof the class described in which partially used abrasive blocks and thelike may be more completely consumed. Other objects will be in partobvious and in part pointed. out hereinafter.

The invention accordingly comprises the elements and combinations ofelements, features of construction, and arrangements of parts which willbe exemplified in the structures hereinafter described, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings, in which are illustrated several ofvarious possible embodiments of the invention,

Fig. 1 is a side elevation of a manually operable form of apparatus forcarrying out the invention;

Fig. 2 is a bottom plan view of Fig. l;

Fig. 3 is a fragmentary end elevation of Fig. 1;

Fig. 4 is a side view of a power-driven form of the invention, partsbeing in section;

Fig. 5 is a bottom plan view of Fig. 4;

Fig. 6 is a perspective view of the apparatus of Figs. 4 and 5, shownattached to a driving head and raised from the surface to be finished;

Fig. 7 is a View similar to Fig. 5 showing a modified form;

- Fig. 8 is a view similar to Fig. 4 showing another form of theinvention; and,

Fig. 9 is a bottom plan view of Fig. 8.

Similar reference characters indicate corresponding parts throughout theseveral views of r the drawings.

When a concrete structure or the like has been poured and has set, andthe forms have been removed, there is presented a surface which does nothave a smooth, dressed appearance. It is therefore desirable to removefrom the surface the marks left by the forms, consisting of offsetmarks, voids, fins, grain pattern and other irregularities.

Heretofore dressing has been done by the use of an abrasive stone or thelike to break the 10 seal or the like which formed on the outside of astructure. Such grinding Works the sand and cement into a mortar whichis used to seal the voids that are formed on the surface of thestructure. The voids are filled by means of a separate trowellingoperation, and with additional surfacing material where necessary. Theadditional surfacing material and additional trowelling operation havebeen made necessary by reason ofthe fact that during the abradingoperation to break the voids, the comminuted material which has beenloosened has been lost, either by blowing away if. dry, or by beingflung away if wet. During the abrading operation it is often thepractice to apply water to .the surface so that the abraded materialfunctions as much as possible as a mortar.

By means of the present invention, the sludge or mortar of comminutedmaterial and water is conserved in situ during the abrading operationand is intermittently trowelled into position during that operation, sothat not only is the number of operations reduced, but a greater amountof mortar-like material is available for finishing.

The invention may be used upon various types of structures, but it willbe described in connection with concrete structures by way of example.

It is applicable to concrete structures of all ages. However, if theinvention is used in connection with structures which have just beenset, it is more advantageous, because then the comminuted concrete is ina condition to re-form into a more durable surface for filling the voidswhich have been left or broken open by abrasion.

Referring now more particularly to Figs. 1-3, which show a manuallyoperable form of apparatus, numeral i indicates a supporting plate uponwhich is formed a handle 3. Passing through openings in the supportingplate l are spacing pillars 5. These pillars are not threaded into theplate I, but are slidable through their openings and are held rigidly inposition by means of oppositely located lock nutsv 'I'. By means of thelock nuts I, the pillars 5 may be adjusted vertically in the supportingplate I.

At their lower ends i, the spacing pillars 5 are fastened into what willhereinafter be referred to as a trowel head or trowel 9 having anonabrasive, smooth bottom surface 2'5. This head is smooth and flatupon its bottom and is of cruciform shape, as shown in Fig. 3. Thus, thesupporting plate and the trowel 9 are fixedly but adjustably related.

At numeral H is shown a carrier or face plate which is flanged at itsedges as at l3 for receiving at its corners a plurality of spacedabrasive stones l5. Each stone is provided on its back with an anchored,interiorly threaded thimble #1. Threaded into these thimbles H are theends l9 of guide studs 2|. The guide studs 2| are therefore rigidlysupported on the plate II and are rigid with respect to the stones |5.The studs pass slidably through openings in the supporting plate I andare thereabove provided with heads 23. Springs 24 reacting between thesup porting plate and the face plate l5 tend to push the latterdownward, and consequently also the stones l5. The limit of motion isdetermined by the heads 23 and is such that the lower surfaces 25 of thestones l5 are normally a substantial distance below the surface of thetrowel 9 (see Figs 1 and 3, for example).

It will therefore be seen that the lower surfaces 25 of the stones |5are resiliently spaced below the lower surface 21 of the cruciformtrowel 9. The pillars 5 pass through the spaces between pairs of stonesl5 and freely through openings in the face plate so that with some addedpressure from the handle 3, the springs 24 may be compressed. Hence, ifthe stones |5 rest upon a concrete surface or the like, the surface 21of I the trowel 9 may be pushed against the concrete at will. Normally,without said added pressure, the stone |5 may be rubbed laterally over aconcrete surface without pushing the surface 2'! flush with the surface25.

The operation of the device of Figs. 1-3 is as follows:

Assume that a concrete has been poured and set and has had the formsremoved. The operator flushes water upon this surface and then appliesthe abrasive stones with a lateral rubbing action which may bereciprocating or more or less spiral or rotary. In carrying out thisaction he may press somewhat upon the handle 3 without substantiallycompressing the springs 24. Thus the low-er surface 21 of the trowel 9remains clear of the surface, while the bottom surfaces 25 of theabrasive stones l5 rub upon the surface and break open the voids justbeneath. At the same time the abraded and comminuted material mixes withthe applied water and forms a mortar-like sludge which, as the rotaryaction continues is substantially conserved in the cruciform channelformed between blocks |5 and beneath the trowel 9. In other words, thissludgelike material does not run away as easily as heretofore.

After the operator has worked up a substantial amount of sludge byhaving effected an abrasion and comminution of a substantial part of thesurface, he continues his lateral motions and at the same time pressesnormally with more force upon the handle 3 to force the trowel surfacepoint 2'! into a plane with the surface 25, that is, against the abraded(and now more smooth) concrete surface. This forces the conserved sludgeinto the voids which have been broken open by the abrasion, and at thesame time smooths out this sludge into a desirable surface. After anarea has been completed in this way, the operator removes his operationsto an adjacent area and continues them.

Ordinarily, if the operations are carried out directly after the formshave been removed from the structure, there is enough remaining settingpower in the cement of the concrete to cause the sludge which has beenforced into the voids to take a final or residual set which resistslater leaching, After ten days or so, the operation over the entiresurface is ordinarily repeated. Finally, after drying, the surfaceappears smoother and whiter, due to the different reflective characterof the implaced comminuted material.

If the operations are delayed until the structure becomes older, forexample, a year or so, then the power of the cement in the sludge totake a final or residual set is gone, and in such event it may bedesirable to add some fresh material to the sludge as it is formed, asby throwing on powdered cement to become absorbed with the sludge andworked in by the trowel 9.

From the above it will be seen that the invention provides for breakingopen surface voids by means of an abrasive, conserving the comminutedmaterial which is abraded away, and in the same operation forcing asludge of the comminuted material into the voids thus broken open.

After a time, the abrasive stones l3 will wear,

thus decreasing the depth of the channel under the trowel 9 and betweenstones l5. To compensate for this, the nuts 7 may be adjusted so thatthe trowel 9 is drawn back toward the supporting plate I the necessarydistance to maintain the channel.

Additional advantages of the invention are that the weight of the deviceis not greatly more than the weight of the so-called rubbing bricksheretofore used. There is a conservation-of stone material because theadjustment mentioned ob- Viates throwing away large pieces of abrasiveblock. Furthermore, the basic mechanism of the device is conserved forwhen the stones are completely worn out they may be removed and newstones applied to the plate In Figs. 4 to 6 is shown another form of theinvention in which a rotary movement is obtained from a power source. Inthis case there is provided a rotary supporting plate 3| which isannular in form and coupled to a hub 33 through a flexible coupler 35made of flexible material such as rubberized layers of fabric. Means forfastening the coupler to the supporting plate 3| are shown at 31. Thehub 33 consists of a flanged and hollow rotary shaft 39 to which isthreaded a hollow flange 4|. These clamp the inner periphery of theflexible coupling 35. The head 4| carries an outlet water nozzle 43which receives water from the hollow shaft 39.

The hollow shaft 39 is driven to rotate from a known type of drivinghead 45 shown in Fig. 6 having a handle 41 and a flexible rotary chaindrive 49 leading from a suitable source of rotary motive power, such asfrom a gasoline power unit. The inlet 4 for the drive 49 also serves asa handle. The heads such as 45 are ordinarily also provided with a waterconnection 5| which supplies water through a suitable interior packinggland to the hollow shaft 39. The details of the drive 49, head 45 andwater connection 5| to the hollow shaft 39 need not be further describedhere, because apparatus of this type is known and available for drivingother devices requiring a water feed. Inserted in the water line at thehead 45 is a water valve control '6.

The supporting'plate 3| will be seen to be provided with adjustable butnormally stationary supports 53 held by lock nuts 55 and carrying attheir outer ends a rotary trowel 51, the trowel being thus spaced andcarried by the supporting plate 3|. A circular protective edge 59 isemployed in connection with spiral arms 6|. The arms 6| terminate in acentral hub 63 in which is a hole 55. The nozzle 43 extends into thehole 65 but short of the outer surface of the trowel 51, Substantialspace exists between the end of the nozzle 43 and the hole 65, toaccommodate the relative movement permitted bythe flexibility introducedby the flexible disc 35.

Numeral 61 indicates a rotary supporting or face plate having .suitablerecesses 69 into which are set abrasive stones l, the latter alsoincluding holding thimbles 13 for threadably receiving studs 15/ Thestuds hold the stones to the plate 51. The studs 15 pass slidablythrough the rotary supporting plate 3| and on the other side areprovided with movement-limiting heads 11. The shapes of the stones areshown in Fig. 5 and their thicknesses in Fig. 4. They are thick enoughso that their lower surfaces 25 are below the surface 21 of the rotarytrowel 51.

Operation of this form of the invention is as follows:

The desired rotation is in the direction shown by the arrow A in Fig. 5,that is, with the curved forms of the trowel arms 6| presenting theirconcavities or pocket shapes in the direction of motion so thatcomminuted sludge material tends to have its centrifugal motioncounteracted by a centripetal action. Thus the region formed between thestones H and below the trowel surface 21 forms recesses in which sludge(made by the grinding of the stones) is conserved. After turning on theengine, the operator presses the rotating head so that the stones 1|abrade the desired surface, water having been turned on at valve 6 inthe desired amount to exude from the nozzle 43 as shown at 8 (Fig. 6).After a substantial amount of abraded sludge is'worked up, more pressureis applied to the handles 4, 41 and head 45 so that the surface 21 ispressed flush with the surface 25, thus causing the trowel 51 to smoothout the sludge and press it into the "voids opened by the stones "H.After a given region has been finished, the operator moves to anadjacent one and continues the operations.

The flexible connector 35 is a refinement for the purpose of makingeasier the alignment of the device; that is, the operator needs notlevel it accurately against the surface with this fiexible connectorbecause it seeks its own level, However, the device may be made withoutsuch a flexible connector, the driving connections between the plate 3|and the hub 33 being rigid as hereinafter indicated.

It is to be understood that, if desired, the device may be driven from arotary head which does not supply water, in which event the water is Asstated, the purpose of the edge portion 59 of the trowel 51 is tosurround the stones H with a metallic guard to prevent the stones frombreaking off upon impact at corners or the like. This guard has theeffect of 'Ihnit'ingthe closeness with which corners of a structure maybe entered, and for the purpose of finishing such corners the device ofFigs. 1-3 may be used; or the alternative construction shown in Fig. 7may be used. In the latter case the trowel 51 is made with the hub 63and with arms 6|. However, the arms are terminated at 19 and no guardportion .59 is used. With such a rimless rotary dresser, corners may beentered, but it needs to be operated with more care so that the stonesare not broken or chipped by impact.

In Figs. 8 and 9 is shown another form of the device in which likenumerals designate like parts. In this case, there is, for example, a.rigid connec tion between the rotary supporting plate 3| and the hub 33.This form of the invention also shows its application to the use ofabrasive star wheels 8|. The face plate 61, in this case, carries metal(aluminum, for example) blocks 83, instead of the stones 1|. Theseblocks in turn carry supporting pins 85 located across sockets 81 in theblocks 83. Each 'pin carries a plurality of freely rotary, renewable,hardened star wheels 8|. These star wheels roll on the concrete surfaceunder medium pressure and function to provide a faster .but coarserdressing than the stones H. The operation is the same as the deviceshownin Figs. 4-7, extra pressure being used to force down the trowel 51 whena smoothing action is desired. Such pressure places surface 21 flushwith the rolling tangent of the star wheels. .In this form of theinvention, the rim 59 may also be left 01f.

It is intended that the metal blocks 83 with their star wheels shall beinterchangeable with the stones II of Figs. 4 and 15 orof Fig. 17.

As to the flexible coupling 35 (Figs. 4-6), there may be substituted a.flexible joint in the drive shaft 39.

Af-teir operations are finished upon a concrete surface with any of theforms of the invention, the sludge which has been trowelled into placein the voids dries land forms a much whiter (crystalline) surface uponthe structure than is obtained by simply permitting the structure tostand or by covering it with cement (without opening the voids) Thecharacter of the stones H and J5 is that of any good block typeabrasive, such assilicon carbide or the like. The angular velocity ofthe head is variable and may be made to suit circumstances of enginespeed, available drives, etc. For example, from '200 to 100.0 orscrewlutions :per minute has been found satisfactory.

It is to be understood that the rotary form of the device may also bedriven from hydraulic, pneumatic or electric apparatus, such as is oftenavailable to contractors in their ordinary building operations.

Another feature of the invention is the use of segmental stones.Heretofore, rubbing stones have been made up in one large stone. In thepresent case, the stones are made more economically in smaller pieces,the conserving channels being obtained by separation.

It will be understood that the, invention is applicable to smoothingother walls, for example masonry, brick, plaster and the like, althoughits primary use is for monolithic concrete.

In view of the (above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As many changes could be made in the above constructions withoutdeparting from the scope of the invention, it isxintended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense,

We claim:

1. Finishing apparatus comprising a movable support, spaced abrasiveelements resiliently connected thereto, a nonaabrasive trowel elementrigidly connected to said support intermediate said spaced abrasiveelements, whereby pressure applied to said support will force the trowelelement into engagement with the surface upon which the abrasiveelements move.

2. Finishing apparatus comprising a rotary support, spaced abrasiveelements resiliently connected thereto for relative axial movement, anon-abrasive trowel element rigidly connected to said supportintermediate said abrasive elements, whereby pressure applied to saidrotary support will, while rotating, force the trowel element intorotary engagement with the surface upon which the abrasive elementsmove.

'3. Finishing apparatus comprising a movable support, spaced abrasiveelements resiliently connected thereto, a non-abrasive trowel elementrigidly connected to said support intermediate said spaced abrasiveelements, whereby pressure applied to said support will force the trowelelement into engagement with the surface upon which the abrasiveelements move, and means attached to the support for directing waterupon said surface where the abrasive elements act.

4. Finishing apparatus comprising a movable support, at least oneabrasive element resiliently connected thereto, a non-abrasive trowelelement rigidly connected to said support adjacent to said abrasiveelement, whereby pressure applied to said support will force the trowelelement into engagement with the surface upon which the abrasive elementmoves, and means attached to the support for directing water upon saidsurface where the abrasive element moves.

5. Finishing apparatus comprising a rotary support, spaced abrasiveelements resiliently connected thereto for axial movement, anon-abrasive trowel element rigidly connected to said supportintermediate said abrasive elements, whereby pressure applied to saidrotary support will, while rotating, force the trowel element intoengagement with the surfac upon which the abrasive elements move, andmeans attached to the support for directing water upon said surfacewhere the abrasive elements act.

6. Finishing apparatus comprising a movable support, spaced abrasiveelements resiliently connected thereto, 5a. non-abrasive trowel elementrigidly connected to said support, said trowel having a portionintermediate and a protective portionv around said spaced abrasiveelements, whereby pressure applied to said support will force the trowelelement into engagement with the surface upon which the abrasiveelements move. I

7. Finishing apparatus comprising a rotary support, spaced abrasivestar-wheel elements resiliently connected thereto for axial movement, a

non-abrasive trowel element rigidly connected to said supportintermediate said star-wheel elements, whereby pressure applied to saidrotary support will, whilerotatingiorce the trowel element intoengagement with the surface upon which the star-wheelelements move.

8. Finishing apparatus comprising a movable support, at least oneabrasive element having a resilient connection therewith, a non-abrasivetrowel element rigidly connected to said support and located adjacentsaid abrasive element, whereby pressure applied to said support willforce the trowel element into engagement with the surface upon which theabrasive element moves, said resilientconnection normally withholdingthe trowel away from said surface.

9. Finishing apparatus comprising a rotary support, spaced abrasiveelements resiliently connected thereto for relative axial movement, anon-abrasive trowel element rigidly connected to said supportintermediate said abrasive elements, whereby pressure applied to saidrotary support will, while rotating, force the trowel element intorotary. engagement with the surface upon which the abrasive elementsmove, said trowel element having a pocket shape concave in the directionof motion to exert a centripetal gathering action on abraded material.

10. Finishing apparatus comprising a rotary supp-ort,spaced abrasiveelements resiliently connected thereto, a non-abrasive trowel elementrigidly connected to said support intermediate said abrasive elementswhereby pressure applied to said rotary support will, while rotating,force the trowel element into engagement with the surfac uponwhicli theabrasive elements move, attached means for directing water upon saidsurface as the abrasive elements act to detach abraded materials, saidtrowel element having a spiral face concave in the direction of rotationto exert a centripetal action upon the mortar formed by the water andabraded materials.

NDLION H, BIRG-ER. CALVIN D. JO I-IENSO'N.

